skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: The Discovery of λ Bootis Stars: The Southern Survey I

Abstract

The λ Boo stars are a class of chemically peculiar Population I A-type stars characterized by under-abundances of the refractory elements, but near-solar abundances of carbon, nitrogen, oxygen, and sulfur. There is some evidence that λ Boo stars have higher frequencies of “bright” debris disks than normal A-type stars. The discovery of four exoplanets orbiting HR 8799, a λ Boo star with a resolved debris disk, suggests that the λ Boo phenomenon may be related to the presence of a dynamic debris disk, perhaps perturbed by migrating planets. However, only 64 λ Boo stars are known, and those stars were discovered with different techniques, making it problematic to use that sample for statistical purposes, including determining the frequency of debris disks. The purpose of this paper is to derive a new sample of λ Boo stars using a technique that does not lead to biases with respect to the presence of infrared excesses. Through spectroscopic observations in the southern hemisphere, we have discovered 33 λ Boo stars and have confirmed 12 others. As a step toward determining the proportion of λ Boo stars with infrared excesses, we have used WISE data to examine the infrared properties of this sample outmore » to 22 μ m. On this basis, we cannot conclude that λ Boo stars have a greater tendency than normal A-type stars to show infrared excesses. However, observing this sample at longer wavelengths may change that conclusion, as many λ Boo debris disks are cool and do not radiate strongly at 22 μ m.« less

Authors:
; ;  [1];  [2];  [3];  [4];  [5];  [6]
  1. Department of Physics and Astronomy, Appalachian State University, Boone, NC 26808 (United States)
  2. Department of Statistics, University of the Western Cape, Private Bag X17, Bellville, 7535 Cape Town (South Africa)
  3. Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006 (Australia)
  4. Vatican Observatory Research Group, Steward Observatory, Tucson, AZ, 85721-0065 (United States)
  5. California State University, Fullerton, Fullerton, CA (United States)
  6. National Science Foundation, Arlington, VA (United States)
Publication Date:
OSTI Identifier:
22663442
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (Online); Journal Volume: 154; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON; ELEMENT ABUNDANCE; EMISSION; NITROGEN; OXYGEN; REFRACTORIES; SOUTHERN HEMISPHERE; STAR EVOLUTION; STARS; SULFUR; WAVELENGTHS

Citation Formats

Gray, R. O., Riggs, Q. S., Newsome, I. M., Koen, C., Murphy, S. J., Corbally, C. J., Cheng, K.-P., and Neff, J. E. The Discovery of λ Bootis Stars: The Southern Survey I. United States: N. p., 2017. Web. doi:10.3847/1538-3881/AA6D5E.
Gray, R. O., Riggs, Q. S., Newsome, I. M., Koen, C., Murphy, S. J., Corbally, C. J., Cheng, K.-P., & Neff, J. E. The Discovery of λ Bootis Stars: The Southern Survey I. United States. doi:10.3847/1538-3881/AA6D5E.
Gray, R. O., Riggs, Q. S., Newsome, I. M., Koen, C., Murphy, S. J., Corbally, C. J., Cheng, K.-P., and Neff, J. E. Sat . "The Discovery of λ Bootis Stars: The Southern Survey I". United States. doi:10.3847/1538-3881/AA6D5E.
@article{osti_22663442,
title = {The Discovery of λ Bootis Stars: The Southern Survey I},
author = {Gray, R. O. and Riggs, Q. S. and Newsome, I. M. and Koen, C. and Murphy, S. J. and Corbally, C. J. and Cheng, K.-P. and Neff, J. E.},
abstractNote = {The λ Boo stars are a class of chemically peculiar Population I A-type stars characterized by under-abundances of the refractory elements, but near-solar abundances of carbon, nitrogen, oxygen, and sulfur. There is some evidence that λ Boo stars have higher frequencies of “bright” debris disks than normal A-type stars. The discovery of four exoplanets orbiting HR 8799, a λ Boo star with a resolved debris disk, suggests that the λ Boo phenomenon may be related to the presence of a dynamic debris disk, perhaps perturbed by migrating planets. However, only 64 λ Boo stars are known, and those stars were discovered with different techniques, making it problematic to use that sample for statistical purposes, including determining the frequency of debris disks. The purpose of this paper is to derive a new sample of λ Boo stars using a technique that does not lead to biases with respect to the presence of infrared excesses. Through spectroscopic observations in the southern hemisphere, we have discovered 33 λ Boo stars and have confirmed 12 others. As a step toward determining the proportion of λ Boo stars with infrared excesses, we have used WISE data to examine the infrared properties of this sample out to 22 μ m. On this basis, we cannot conclude that λ Boo stars have a greater tendency than normal A-type stars to show infrared excesses. However, observing this sample at longer wavelengths may change that conclusion, as many λ Boo debris disks are cool and do not radiate strongly at 22 μ m.},
doi = {10.3847/1538-3881/AA6D5E},
journal = {Astronomical Journal (Online)},
number = 1,
volume = 154,
place = {United States},
year = {Sat Jul 01 00:00:00 EDT 2017},
month = {Sat Jul 01 00:00:00 EDT 2017}
}